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ASME B31.3-2016
<br /> (16) 320.2 Stress Due to Sustained Loads The equation for the stress due to sustained longitudinal
<br /> The equation for the stress due to sustained loads, force, SQ,is
<br /> such as pressure and weight,SL,is provided in eq. (23a). S = IF, 23d
<br /> Equations for the stress due to sustained bending a q a ( )
<br /> P
<br /> moments, Sb, are presented in eqs. (23bl) and (23b2).
<br /> where
<br /> SL = (WSJ+Sb)2+(2St)7 (23a) AP = cross-sectional area of the pipe, considering
<br /> nominal pipe dimensions less allowances; see
<br /> (` �)I M Z+ IM�)Z para. 320.1
<br /> Sb — Z (� (23b1) FQ = longitudinal force due to sustained loads, e.g.,
<br /> pressure and weight
<br /> IQ = sustained longitudinal force index. In the
<br /> For branch (Leg 3 in Fig. 319.4.413), use eq. (23b2) only absence of more applicable data,IQ is taken
<br /> when Ii or Io is based upon i, ii, or io taken from as 1.00.
<br /> Appendix D; when both Ii and Io are determined by
<br /> experimental or analytical means,e.g.,ASME 1331J,use The sustained longitudinal force, FQ, includes the sus-
<br /> eq. (23bl). tained force due to pressure, which is PjAf unless the
<br /> piping system includes an expansion joint that is not
<br /> (JM,)2+(JoMj2 designed to carry this force itself,where Pj is the internal
<br /> Sb = Ze (23b2) operating pressure for the condition being considered,
<br /> Af= -ad 2/4,and d is the pipe inside diameter considering
<br /> where pipe wall thickness less applicable allowances; see
<br /> h = sustained in-plane moment index. In the para. 320.1. For piping systems that contain expansion
<br /> absence of more applicable data,Ii is taken as joints,it is the responsibility of the designer to determine
<br /> the greater of 0.75ii or 1.00. the sustained longitudinal force due to pressure in the
<br /> Io = sustained out-plane moment index. In the piping system.
<br /> absence of more applicable data,to is taken as
<br /> the greater of 0.75io or 1.00. 321 PIPING SUPPORT
<br /> Mi = in-plane moment due to sustained loads,e.g., 321.1 General
<br /> pressure and weight
<br /> Mo = out-plane moment due to sustained loads,e.g., The design of support structures (not covered by this
<br /> pressure and weight Code) and of supporting elements (see definitions of
<br /> Z = sustained section modulus. Z in eqs. (23bl) piping and pipe supporting elements in para. 300.2)
<br /> and (23c) is described in para. 319.4.4 but is shall be based on all concurrently acting loads transmit-
<br /> computed in this paragraph using nominal ted into such supports.These loads,defined in para.301,
<br /> pipe dimensions less allowances; see include weight effects,loads introduced by service pres-
<br /> para. 320.1. sures and temperatures, vibration, wind, earthquake,
<br /> shock, and displacement strain (see para. 319.2.2).
<br /> Ze sustained effective section modulus. Ze in eq. For piping containing gas or vapor,weight calculations
<br /> (23b2) is described in para. 319.4.4, using i�from Appendix D in Ts calculation, but Ze is need not include the weight of liquid if the designer has
<br /> taken specific precautions against entrance of liquid into
<br /> computed in this paragraph using nominal thepiping, and if the piping is not to be subjected to
<br /> pipe dimensions less allowances; see p p g
<br /> para. 320.1. hydrostatic testing at initial construction or subsequent
<br /> inspections.
<br /> The equation for the stress due to sustained torsional 321.1.1 Objectives. The layout and design of piping
<br /> moment, St,is and its supporting elements shall be directed toward
<br /> preventing the following:
<br /> _ I'Mt (a) piping stresses in excess of those permitted in
<br /> St 2Z (23c) this Code
<br /> (b) leakage at joints
<br /> where (c) excessive thrusts and moments on connected
<br /> It = sustained torsional moment index. In the equipment (such as pumps and turbines)
<br /> absence of more applicable data, It is taken (d) excessive stresses in the supporting (or
<br /> as 1.00. restraining) elements
<br /> Mt = torsional moment due to sustained loads,e.g., (e) resonance with imposed or fluid-induced
<br /> pressure and weight vibrations
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